Transmission



April 2E, i959 J. B. PoLoMsKl TRANSMISSION 2 Sheets-Sheet 1 Filed Dec. 28, 1953 K www ww www MMIIQVJ ENNL.

fraz/e of# .F. I l NNN rwll- April 21, 1959 J. B. PoLoMsKl 2,882,756

- TRANSMISSION F'ilednec. 2s, 1953 2 sheets-sheet 2 nited States TRANSMISSION John B. Polomski, Detroit, Mich., assignor to Borg- Warner Corporation, Chicago, Ill., a corporation of Illinois Application December 28, 1953, Serial No. 400,554

Claims. (Cl. 74-754) The invention relates to transmissions for automotive vehicles and more particularly to such transmissions including hydraulic torque converters transmitting relatively large torque under stall conditions which decreases automatically and gradually as the vehicle starts from rest and increases in speed.

Such transmissions are now in general use in automotive vehicles. The transmissions generally include gearing connected in tandem with the hydraulic torque converter providing a number of power trains of different speed ratios. Speed responsive governor mechanism is provided in connection with the gearing which functions to change the gearing from a low speed ratio to a higher -speed ratio as the speed of the vehicle increases.

The power trains through the gearing are generally completed by friction engaging mechanisms, such as friction clutches or brakes, and such friction engaging mechanisms must be suiicient in effect to take the increased torque provided by the hydraulic torque converter under stall conditions as the vehicle is being started.

It is an object of the present invention to provide a pair of friction engaging mechanisms which both complete a low speed power train through the gearing and which are both effective when the vehicle is being started for taking the increased torque due to the large torque transmitted by the hydraulic torque converter under stall conditions. It is a further object to provide governor means, preferably responsive to the speed of the transmission driven shaft for disengaging one of these friction engaging mechanisms when a predetermined low vehicle speed is reached, rendering the other friction engaging mechanisms solely effective to maintain the low speed power train completed. It is contemplated that the governor mechanism rst mentioned shall subsequently change the drive through the gearing from the low speed power train to a higher speed power train. The low speed power train shall preferably include a one-way engaging device, and the higher speed power train shall preferably include a friction engaging mechanism completing the higher speed power train, so that the low speed power train is automatically broken by the one-way device when the higher speed power train is completed by engagement of the friction engaging mechanism.

The governor means for disengaging one of the low speed friction engaging mechanisms preferably takes the form of a valve subject to the output pressure of a pump driven by the driven shaft of the transmission, and it is an object in connection with this valve to provide a connection for interlocking purposes with the higher speed ratio friction engaging mechanism to prevent an engagement of this low speed friction engaging mechanism whenever the higher speed power train is completed.

The invention consists of the novel constructions, arrangements and devices to be hereinafter described and claimed for carrying out the above stated objects and such other objects as will appear from the following description of a preferred embodiment of the invention, illus- F ICC 2- trated with reference to the accompanying drawings, wherein:

Fig. 1 is a schematic illustration of a transmission for installation in an automotive vehicle and a portion of a controlling system for the transmission which embodies the principles of the invention;

Fig. 2 is a schematic illustration of the remainder of the transmission controlling system adapted to be con'- nected to the portion of the system shown in Fig. 1; and

Figs. 3, 4 and 5 are sectional views taken respectively on lines 3 3, 4-4 and 5-5 in Fig. 1 in the directions' indicated.

Like characters of reference designate like parts in the several views.

Referring now to the drawings, the transmission illustrated comprises a drive shaft 10 and a driven shaft 11. The drive shaft 10 is adapted to be driven by the engine 12 of the vehicle in which the transmission is installed, and the driven shaft 11 is adapted to drive the rear road wheels 13 of the vehicle through any suitable drive connections.

The transmission comprises in general a hydraulic torque converter 14, a planetary gear set 15, a second planetary gear set 16, a forward drive brake 17, a low speed lockup brake 18, a reverse brake 19, a high speed forward drive clutch 20 and an intermediate speed clutch 21.

The hydraulic torque converter 14 comprises a bladed impeller 22, a bladed runner or driven element 23 and a bladed stator or reaction element 24. The impeller is connected to be driven from the drive shaft 10. The stator 24 is connected to a one-way brake 25 which is effective for holding the stator 24 against rotation in the reverse direction, that is, in the direction of rotation opposite to that of the drive shaft 10. The brake 25 may be of any suitable construction and may, for example, comprise tiltable sprags 26 disposed between and engageable with inner and outer cylindrical raceways 27 and 28 as shown in Fig. 3.

The planetary gear set 15 comprises a ring gear 29,

a sun gear 30, a plurality of planet gears 31 in mesh with the sun and ring gears and a planet gear carrier 32 for the planet gears 31. The second planetary gear set 16 comprises a ring gear 33, a sun gear 34, a plurality of planet gears 35 in mesh with the sun and ring gears and a planet gear carrier 36. 'Ihe ring gear 29 of the rst planetary gear set is connected to be driven by the runner 23 of the torque converter 14, and the planet gear carrier 32 of this gear set is connected with the ring gear 33 of the second planetary gear set 16. The planet gear carrier 36 of the second gear set is connected with the driven shaft 11.

The friction brake 17 comprises a brake band 37 engageable with a drum 38, and the brake 17 is effective through a one-way brake 39 for braking the sun gear 34 and is effective through a second one-way brake 40 as well as the rst one-way brake 39 disposed in series with the brake 40 for braking the sun gear 30. The one-way brakes 39 and 40 may be of any suitable well-known construction and may be of the sprag type similar to the brake 25. The one-way brake 39 comprises sprags 41 engageable with inner and outer cylinderical surfaces 42 and 43, and the brake 40 comprises sprags 44 engageable between inner and outer cylindrical races 45 and 46. Looking in the same direction at the brakes 39 and 40, the sprags of the two brakes are disposed in opposite directions between the inner and outer races as is apparent from Figs. 4 and 5.

The brake 18 comprises a brake band 47 engageable on a brake drum 48 for augmenting the braking action of the one-way brakes 39 and 40 and the friction brake 17 on the sun gear 30. The friction clutch 21 comprises discs `49`rotatable v`vviththe planet gear carrier 32, discs U rotatablewith thesungearl), opposite pressure plates 51 and 52, and a duid pressure actuated piston S3 for movingthe plate 52 `togvwardlthe plateSl to frictionally e'ri'gag'ethe `'t'wo sets of friction 'dises 'with each other for engagingthe clutch 2:1.

'lfhefr'e'verse brake 19 comprises 'abrakeband 54 engageablelwith 'a brake drum 55 connected with the carrier 32`ofthe planetary gear set 1S and`with theiring gear 33 of the planetary gear set 16. The clutch 2t) comprises aclutch disc 56 lconnected with the driven shaft '11 and anaxially movable pressure plate 57'liaving a iluid pressufre Aactuated piston portion 58 and an axially stationary pressure/plate S9 both rotatable with the drive shaft 1t) andbetweenwhich the disc v56 is engaged.

Each of the brakes `17, 18 and 19 is engaged by a fluid pressure actuated vSe"r'vi'irotr, `lthe brakes 17, 13Y and 19 being respectively l,engagedby servomotors 6 0, `61and"`62- Illiefservojmotor x60 comprises a uid pressure actuated pistn63 forengagingthe brake band 37 on the drum 38,;vf`tl1'efservornotor '61 comprises uid pressure actuated pistons'64andforengaging the brake band 47 onthe Yand the Vservomotorf'62` comprises pistons 66 and 67`for engaging the brake band 54 on'the drum 55. lleturnsprings 6 8, 69 and 70 are provided in the motors 60,"61"an`cl 62 respectively for disengaging the bands from the drums.

In operation, the transmission provides, low, intermediate and direct forward speed drives and a drive in reverse. The'transmission, Whenthe' clutches 20 and 21 and the brakes 17, 18 and 19 are all disengaged is in a neutral condition,` and the shaft 11 is'not driven from the shaft when thelatter is rotated from the` engine 12. The lwspeedforward drive is completed when the brake 17 isengaged, and the brake 18 may also be engaged for this drive for helping the brake 17 take the reaction from the gearing. The sun gear 34 is braked from rotation by means of the friction brake 17 and the one-way brake 39, and the sungear 30 is braked through the one-way brake 40 from the sun gear 34. When the brake 18 is also engaged, this brake also brakes the sun gear 30.

The runner 23 in the torque converter 14 is driven through the medium of the fluid in 'thel torque converter from the impeller 22 and the drive shaft 10. As is well known iin connection with such hydraulic torque converters, the torque output from such a converter is initially very high under stall conditions'when the runner is stationary, andthe torque output of the torque converter decreases gradually as the speed of the runner increases. It `is* usual with such converters that the torque multiplici'ation may initially be about 2.221, for example, and decrease to lzlwith increases in runner speed.

v'l`hefrunrier 23 drives the ring gear 29 of the gear set 15'. The sun gear 30 of this gearset is braked to be stationary,'as has just been described, and the planet gears 31 planetate between the sun gear 30 and ring gear 29 to drive the carrier 32 at a reduced speed and increased torque in the forward direction. The ring gear 33 of thesecond planetary gear set 16 is connected with the carrier 32 and is driven thereby. Thesun gear 34 of the gear set 16 is braked to be stationary, as has just been described, and the planet gears 35 of this gear set planetate between the ring gear 33 and the sun gear 34 and drive'the planet gear'carrier 36, which is connected with the driven shaft 11, at a further reduced speed and increased torque in the forward direction. The driven shaft 11'is thus driven at an increased torque with respect tothatimpres'sed on the drive shaft 10, an increase in torquejtaking place ineach of the hydraulic torque converte y'14, the"planetarygear set 1S and the planetary gearset 16.

Intermediate speed forward drive through the transmissionis'completed by disengaging the brake 18 and engagingthe clutch 21. The clutch 21 connects together the p'l'anetgear carrier 32 and the sun gear 30 of the planetary gear set thereby locking up the gear set and causing all of its elementstorotate together "as a unit. The ring gear 33 of the second planetary gear set 16 is thereby driven from the runner 23 at the same speed as the runner, and the speed of the driven shaft 11 is thereby increased with respect to its speed in low speed forward drive.

Direct drive through the transmission is completed by engaging the clutch which directly connects together the drive shaft 10 with the driven shaft 11. Both the clutch 21 and the brake 17 may be allowed to remain'in engaged condition for this drive.

Reverse drive is completed through the `transmission by engaging the reverse brake 19. The brake 19 functions to hold stationary thefplanet gear carrier 32 of the gear set 1S and the ring gear 33 of the gear set 16 connected with the carrier 32. The ring gear 29 is driven as in the forward drives through the hydraulic torque converter 14v from the drive'shaft 10, and the sun` gear v30 is driven at areduced fsp'eed inthe reverse direction through the intermediary of the planet gear pinions 31 heid against planetary rotation about the centers of the shafts 10 land 11 by the brake 19. The sun gear '30 drives the sun gear 34 of the planetary gear set 16 through the one-way brake 40 which'now functions as a clutch. The ring gear 33 of the gear set 16 being held stationary by the reverse brake/19 functions as the vreaction element of the gear set 16 to lcause a drive'of the planet gear carrier v36 and thereby the driven shaft 11 in the reverse direction at a speed which is reduced below the speed lof the sun gear 30 due to the action of the planet gear pinions 3S rotating within the ring gear 33.

The controlmechanismfor the transmission comprises in general a shuttle valve 77, a converter valve 78, `a reverse interlock valve 79, a pum-p- 8th driven by the drive shaft 1i) of the transmission, a pump'Sl drivenby the driven shaft 11 of the transmission, a manual selector valve 82, a governor`valvev83, a front pump reliefvalve 84 and a rear pump relief 'valve 85. l

The drive shaft pump comprises an inner gear L86 driven through the intermediary of the impeller 22 'of the torque converter 1d from the drive shaft 10 and an outergear87 yeccentrically` located with respect tothe inner gear '86 and in mesh with the latter gear. A crescent shaped casing portion 88`separates the gears 86 and ,87, as shown. The pump 80 is connected with an 'inlet conduit 89 'and thereby with a fluid sump 9d, and thel pump is also connected with anoutlet conduit 91. The pumpis of a well-known construction and'operates as -is well understood to pump fluid from the conduit 89 to the conduit 91'When the inner gear'86 is.' rotated ina clockwisedirection as viewed on the drawing'and the outer gear 87 rotates in the same direction due to its meshing engagement with thev gear S6, the pumping action being due to theuid carried by the gears-86 and`8l' across the inner and outer faces of the crescent shaped casing'portion 88. v

The driven shaft pump l'comprises a gear 92 driven by the driven shaft 11in mesh'with a gear 93. The pump Slis connected with an inlet conduit y94 which is connected to draw iluid out of the sump 9d, and the pump is connected with an outlet-conduit 95. Thepum'p 81 also is of well-known construction and operation, carrying iuid between its gear teeth to provide its pumping action.

The outlet conduit 91 of the drive shaft purnpSG is connected with the rear pump relief valve 35,- as shown. The valve 8S comprises a piston slidably disposed in a casing portion 97. The piston 96 has lands 98 and 99 .and agroove llltlbetween the lands. vThe casing portion l97 is provided with a port 101, two connected ports 132, aport 103 and two connected ports 104, as shown, and it has connected cavities 105 and 106`of respectively larger and smaller diameters in which the lands'98 and 99 are t respectively'slidble. 'A compression spring" 107 is provided between the lower end of the piston 96 and the lower end of the cavity 105.

A regulated uid pressure supply conduit 108 is connected by means of a branch conduit 109 with the ports 102 and the outlet conduit 91 for the pump 80. A check valve 110 comprising a ball 111 adapted to rest on a seat 112 is provided in the conduit 109 for allowing fluid to ow through the conduit in only one direction. The ports 101 and 103 of the valve 85 are bleed ports adapted to freely discharge fluid into the sump 90.

The front pump relief valve 84 is connected with the conduit 109, as shown, and comprises a hollow piston 113 slidably disposed in a casing portion 114. A piston 115 is slidably disposed in a bushing 116 fixed Within the casing portion 114 and is connected by a reduced diameter stern portion 117 with the piston 113. The casing portion 114 has ports 118 and 119, as shown, the port 119 being a bleed port for freely discharging uid into the `sump 90. The bushing 116 and the casing portion 114 have connected cavities 120 and 121 of respectively smaller and larger diameters in which the pistons 115 and 113 are respectively slidable, and the cavity 121 at its upper end is connected to the conduit 109. A spring 122 is provided between an internal ridge in the bushing 116 and the inner end of the piston 113.

The outlet conduit 95 for the pump 81 is connected with one of the ports 104 in the valve 85 by means of a branch conduit 123, and the conduit 95 is also connected with the regulated pressure conduit 108 by means of the branch conduit 123. A check valve 124 is provided in the conduit 123 and comprises a ball 125 adapted to rest on a seat 126.

The regulated uid pressure conduit 108 is connected with the manual selector valve 82. Ihe valve 82 cornprises a valve piston 127 slidably disposed in a casing portion 128. The piston 127 is provided with lands 129, 130, 131 and 132 and grooves 133, 134 and 135 between the lands. The casing portion is provided with ports 136, 137, 138, 139, 140, 141, 142 and 143. The port 141 is a bleed port through which fluid may freely discharge into the sump 90, and the port 137 is connected with the regulated fluid pressure conduit 108. The port 140 is connected by means of a conduit 144 with the shuttle valve 77 as will hereinafter be more fully described. The ports 139 and 142 are connected by means of a conduit 145 with the brake servomotor 60 for applying pressure at times to the piston 63, and the port 143 is connected by means of a conduit 146 with the brake servomotor 62 for applying pressure to the pistons 66 and 67. 'I'he port 136 is connected to the port 118 in the front pump relief valve 84 by means of a conduit 147.

The port 138 in the selector valve 82 is connected by means of a conduit 148 with the valve 83. The valve 83 comprises a valve piston 149 slidably disposed in a casing portion 150. The piston 149 is provided with lands 151, 152 and 153 and grooves 154 and 155 between the lands. The casing portion 150 is provided With ports 156, 157, 158 and 159. The port 159 is a bleed port adapted to freely discharge fluid into the sump 90; the port 156 is connected with the conduit 148; the port 157 is connected by means of a conduit 160 with the pressure piston 53 of the friction clutch 21; and the port 158 is connected by means of a conduit 161 with the pressure plate piston portion 5S of the friction clutch 20.

The shuttle valve 77 comprises pistons 162 and 163 slidably disposed in a cylindrical cavity 164 provided in a casing portion 165. The piston 162 is formed with lands 166 and 167 separated by a groove 168, and the piston 162 is provided with a hollow in one end in which a compression spring 169 is provided. The spring 169 extends between the left end of the cavity 164 and the inner end of the hollow in the piston 162.

The casing portion 165 is provided with ports 170, 171, 172, 173, 174 and 175. The ports 170 and 171 are connected to the conduit 144; the port 172 is con# nected by means of a conduit 176 with the servomotor 61 for applying fluid pressure behind the pistons 64 and 65; the port 173 is connected with the conduit 145; and the port 174 is connected with the outlet conduit 95 from the driven shaft pump 81 by means of a branch conduit 177 and is connected with a supply conduit 178 for the torque converter 14 by means of branch conduits 179 and 180. A check valve 181 is provided between the branches 180 and 179 and comprises a ball 182 adapted to rest on a seat 183. The branch conduit 179 is relatively restricted by being of a smaller diameter, as is shown. The port 175 is connected by means of a conduit 184 with the conduit 160.

The converter valve 78 comprises a valve piston 185 slidably disposed in a cylindrical cavity 186 provided in a casing portion 187 and a piston 188 slidably disposed in a connected, cylindrical, larger diameter cavity 189. The piston is provided with lands 190 and 191 separated by a restricted portion 192, and a passage 193 is provided from the portion 192 to the left end of the piston 185 as shown. A compression spring 194 is provided between the piston 185 and the piston 188.

The casing portion 187 is provided with ports 195, 196, 197 and 198. The ports 196 and 198 are connected by means of a conduit 199 with the pressure supply conduit 108, and a restriction 200 is provided in connection with the port 198 as shown. The port 197 is connected with the converter supply conduit 178.

The reverse interlock valve 79 comprises a piston 201 slidably disposed in a cylindrical cavity 202 provided in a casing portion 203. The piston 201 is provided with lands 204 and 205 separated by a groove 206. A compression spring 207 is provided between the right end of the piston 201 and a spring retainer 208 fixed in an end of the cavity 202. The casing portion 203 is provided with ports 209, 210 and 211. The port 209 is connected by means of a conduit 212 with one of the ports 104 of the rear pump relief valve 85; the port 210 is a bleed port adapted to freely discharge into the sump 90; and the port 211 is connected by means of a conduit 213 with the port of the converter valve 78 and by means of a branch conduit 214 with the conduit 147.

The valve piston 149 is moved between its various positions by means of the combined influence of a governor 215 and the accelerator 216 of the vehicle. The governor 215 comprises ily balls 217 connected by links 218 with hubs 219 and 220 which are separated by a compression spring 221 and are splined and slidableon a shaft 222. The shaft 222 is driven in timed relationship with the driven shaft 11 of the transmission by means of gearing 223. The hub 219 has a slot'224 formed therein for receiving one end of a bell crank 225 actuated through a link 226 from the accelerator 216. The hub 220 is formed with a slot 227 receiving a bar 228 xed to the piston 149 for transmitting the movement of the hub 220 on the shaft 222 to the piston 149.

A restricted outlet is provided for the lluid pressure in the torque converter 14. This is shown as taking the form of a check valve 229 comprising a ball 230 on a seat 231 by a spring 232. The check valve 229 is in a restricted conduit 233 leading yfrom the torque converter 14 to various parts of the transmission which require lubrication. The spring 232 in the check valve is suflcient for maintaining a predetermined low pressure, such as tive lbs. per square inch within the torque converter when the system is inoperative to assure that the torque converter remains full of fluid.

The operation of the transmission and its controls as so far described is as follows: The transmission is conditioned for various types of operation by moving the manually operated selector valve piston 127 into any of its various positions which are the N or neutral position, the D or drive range position, the L or;

assavse low-ra`nge position and the fR or vreverse drive ,position, all of which `are indicatedin the drawing. When the valve rpiston -1-27is in its N or neutral position, there is 'no -drive between-theshafts 10 and 11. `It is assumed that the vehiclefengine r12-is in operation, and the pump '80 which is driven through the impeller 22 from the drive shaft 10draws uidfr'om the sump 90 through the `conduit 89 and discharges itfinto theconduit 91. `It flows betweenthe opposite ports `10Z.finthe valve 85 and through the "conduit 109 into theregulated fluid pressuresupply conduit 108. Thecheck valve 110 is opened by the uid from the :pump '80 with the ball 111 being moved off the seat-11210 providercommunb cation through the conduit l109 to 'lthe conduit 108. The pressurein the conduits r109 and-108=is-maintained at-a :predetermined maximum by means -of 'the front pump lrelief valve-`l84. The pressure Linrtheconduit 109 is yimpressed onthe upper vendof the Ivalve..piston l113 and moves the -valve piston 113 into 'substantially its illustrated port cracking position inwhich the piston-113 allows fluid from the conduit v109 toflow through the bleed -port `119andrthereby tothe sump 90, this movement of the valve piston 113 into port cracking yposition being against the action ofthe spring 122. As will be apparent, a'decrease influid pressure inthe conduit 109 will allowthe piston 113 to moveupwardly under the -inuence of the vspring Y-122 to decrease'the .port cracking effect of the piston 113, `andian increase-in the iiuid pressure in the conduit 109 functionsto move the valvepiston `113 farther downwardly lagainst-the action ofthe spring 122 to increase the port crackingfeffect of the lpiston 11'3, so that the n'et eiect of thev'alve 84 is tolmaintain the uid in the conduits 109 and108at a predetermined maximum pressure. In the neutral'position ofthe selector valve piston 127,-however,the'land 129 of this piston blocks the port 137 for the conduit108, so that this lluidpressure does not pass through the selector valve-82'to any of the brakes orclutches inthe transmission forengagirig'them. The-drivenV shaft 11 is assumed to be stationary, and the pump 811therefore provides no output liuid pressure in its lconduit 95.

Ordinary forward driving by means of the illustrated transmission is done in drive range, in which the selector valve piston 127 is in its D position. In this position of the piston'127, driving isinitially through thelow speed power train, anda changein speed ratio to Vintermediate speed'drive and finally to'highspeed -drive is obtained as the speed of the vvehicle increases, this upshifting actionof the transmission being obtainedfdue to 'the f action of the governor `215 on :the lgovernor valve S3. `In the D position ofthe selector vvalve piston Y127, regulated pump pressure fromthe conduit 108`is conducted by means of the groove 133 and: ports 137 and 138 to the conduit 148, and fluid under pressure also ows ythrough the groove 133 and port-142 to the conduit 145. The conduit 145 is connected with the servomotor 60 for the forward drive'brake 17,v and the brake`17 is thus applied by application of fluid pressure to the servo piston63. The iluid pressure in the conduit 148 'ows through the port 156 in thev governor valve83 but is 'blocked'by the lands 151 and 152 of the governor .piston V149 in thefillustrated low :speed position of the piston 149.

The fluid pressure-in the conduit'145 is also applied tothe low brake servomotor 61 through -the shuttle valve 77, the 1iluid under pressure flowing Vthrough' the port- 173, the groove`168, the port 172 and the conduit 176 to'the servornotor 61. Thus, both the brakes 17 and 18 are engaged, and the low speed forwarddrive through the transmissionis completed. As -has been previously described, therbrake 17 takes the reaction from the sungear- 34 through'theone-way 'devicef 39, and the' brake 18 takes-'at least a. part :of the reaction from thefsun-g'ear 30,` so that both brakes -augmentfthe actionof`- each-other in" completing-thi-sdrive, and the 8 combined braking effect of the two brakes .17 yand 1-8 is sufficient so that slippage of the brakes does not occur even with the high torquebeing transmittedfrom the torque converter Vu14 as `the 'vehicle starts in low speed drive.

The driven shaft pump 81, as the driven shaft 11 begins rotation, delivers iluid to its discharge conduit 95, and draws fluid from the sump through its inlet conduit 94. The driven shaft pump pressure in the conduit is applied through the branch conduit 177 and the port 174 to the right end of the shuttle valve piston 162 tending to move the shuttle valve piston 162 toward the left against the action of the spring 169. Whenvthe speed of the vehicle and the iiuid pressure output of the driven shaft pump 81 increase sufficiently, at approximatelyve or ten-miles an hour'vehicle speed ina certain embodiment of the invention, the fluid pressure applied to the`right end of thepiston V162 is sucient to move the piston against the action of the spring169 to close the port 173 and open the port 172 with respect to the port 171. Application of fluid pressure to the low speed brake servomotor 61 from the conduit 145 thus ceases, and iluid is drained from the servomotor -61 through the conduit 176, the port 172, the groove 168, the port 171, the conduit 144, the port 140, the groove 134 and the port 141 to the sump-90. Thus, -at this time, after movement of the vehicle has started and the torque output of the hydraulic torque converter 14 has decreased in accordance with the well known principles of operation of suchconverters, the brake 18 is disengaged, and the forward speed brake 17 is solely effective to take the reaction of the ,transmission gearing. The brakev17 is sufcient .in effect to take this reaction due to the decrease in torque output of the torque converter 14.

The uid pressure in the'conduit 95 is impressed on the upper end of the valve piston 96 of the reali pump relief valve 85 through the conduit 123 and tends to move the valve piston`96 downwardly against the action of the spring 107. When the pressure in the conduit 95 has increased suiciently, such movement of the piston 96 takes place, so that the [land 99 of the piston 96 moves out ot the cavity 106 to provide a cracking or small opening between the lower edge 106a of the cavity 106 and the upper edge 99a of the land 99 to thereby provide a limited communicatiou between the bleed port 103 and the conduit 123. The valve piston 96 regulates the pressure to a predetermined'maximum in the conduits 95 and 123. similar to the regulating action of the valve piston 113 of the pressure in the conduit 109 as previouslydescribed, tending to return to its illustrated position and close the communication between the ports 103 and'104 with any decline ink pressure in the conduit 95 to reduce the uid bleed tothe'sump through the port 103'and tending to open farther with any increase in pressure in the conduit 95 to increase the bleed to the sump. The Valve piston 96, when so moved to vent the port 104 to the port 103 and regulate the pressure in the conduit 95, connects the ports 102 and 103, with no restriction, by means of its groove 100,*and any duid discharged by the pump 80 thus ilows freely through the bleed port 103 in the valve S5 to thereby deactivate the drive shaft pump SO-and materially reduce'theamount of power required for driving the pump 80. Under these conditions, with the driven shaft pump 81 supplying substantial fluid under pressure, the check valve 125 is opened by the uid pressure in the conduits 95 and 123, with the ball 125 moving olf its seat'126, and the regulated pressure in the conduits 123 and 108 is supplied by the driven shaft pump 81, exclusive of the drive-shaft pump 30. Since the output' conduit 91 of the drive shaft pump 80 is connected bymeansof .the valve 85 with thebleed port 103, Ithere is no liuid under pressure in the portion of the conduit 109 between the check valve 110 `and the valve 85 tending' to holdl the check valve110 open, fand the check valve 110'closes with itsballmoving on 'to the seat 112 to prevent any of the fluid in the conduit 108 draining through the groove 100 in the valve 85 and the bleed port 103 to the sump 90.

The torque converter 14 is supplied with fluid under pressure Ifrom the supply conduit 108 and the converter valve 78. The pressure in the conduit 108 flows through the conduit 199 and through the restriction 200 to the right end of the converter valve piston 185 and moves the piston 185 to the left as seen in Fig. 2 against the action of the spring 194, so that a limited amount of Huid may ow through the port 196, the groove 192, and the conduit 178 to the torque converter 14. The pressure in the conduit 178 applied to the torque converter passes through the passage 193 to the left end of the valve piston 185 to assist the spring 194 in moving the piston 185 to the right, tending to close the port 196, the net effect of the piston 185 being to supply fluid under a reduced pressure to the conduit 178 and the torque converter 14. There is a slight flow through the torque converter, the fluid being released from the torque converter lby the passage 233 and valve 229. The converter supply conduit 178 is connected directly with the output conduit 95 of the rear pump 81 by means of restricted conduit 179 and conduit 180, so that the rear pump gradually takes up the burden of supplying uid through the hydraulic torque converter 14 prior to the time the piston of the rear pump relief valve 85 moves downwardly to relieve the front pump 80 and allow the rear pump to supply the fluid pressure for the system. A more stable movement and action of the valve 85 is thus obtained.

As the speed of the vehicle increases, the y balls 217 tend to move outwardly to move the hub 220 toward the hub 219 against the action of the spring 221. This movement of the hub 220 causes a corresponding movement of the valve piston 149 into its second speed position in `which the groove 154 connects the ports 156 and 157.

The governor 215 as a whole, however, is changed in position in accordance with the movement given the accelerator 216, the governor being moved downwardly as seen in the figure by an increased depression of the accelerator and consequent increased opening of the engine throttle, so that a lgreater speed of the vehicle is necessary to cause this movement of the valve piston 149 with such accelerator depression. The movement of the governor valve piston 149 is thus under the combined control of the accelerator 216 and governor 21S.

When the piston 149 is in its second speed position connecting the ports 156 and 157, the fluid pressure in the conduit 148 flows through these ports and the conduit 160 to the piston 53 of the second speed clutch 21 to engage this clutch, and the transmission is then in second speed forward drive.

The piston 163 of the shuttle valve 77 is connected by means of the conduit 184 with the conduit 160, so that the uid pressure applied to the second speed clutch 21 is also applied to the piston 163. The pistons 163 and 162 are thus moved to the left against the action of the spring 169,- so that the `land 167 of the piston 162 blocks the port 173 as long as the second speed clutch 21 is engaged and prevents engagement of the brake 18 in intermediate drive even with substantial `decreases in vehicle speed.

A change from second or intermediate to third speed drive is obtained when the speed of the vehicle increases still further with respect to the accelerator depression so that the governor 215 is effective to move the governor va'lve piston 149 into its third speed position in which it connects all three ports 156, 157 and 158. In the changed position of the valve piston, the groove 154 of the piston provides communication :between the conduit 148 containing regulated fluid pressure and the conduit 161 for thereby applying regulated pump pressure to the clutch pressure plate 57. The clutch 20 will thus be applied, and the transmission will be in direct drive.

Low speed drive through the transmission is obtained by moving the manual selector valve piston 127 into its L position in which the groove 133 connects the ports 137 and 142 and the groove 135 connects the ports 139 and 140. The regulated uid pressure in the conduit 108 is supplied through the port 137, the groove 133 and the port 142 to the conduit 145 and the forward brake servomotor 60, and the brake 17 is thus applied. The fluid pressure in the conduit 14S also passes through the port 173, the groove 168, and the port 172 in the shuttle valve 77 and through the conduit 176 to the servomotor 61 to the low lockup brake 18, engaging the brake 18 and providing a two-way drive between the torque converter 14 and the driven shaft 11. The fluid pressure in the conduit 145 also passes through the port 139, the port 140 and the conduit 144 to the port 170 of the shuttle valve to hold the valve piston 162 of the shuttle valve in its illustrated position connecting the ports 172 and 173, the uid pressure on the left end of the valve piston 162 assisting the spring 169 and holding the piston in this position. The low speed brake 18 is thus maintained in engagement for the L position of the selector valve 82 regardless of increases in vehicle speed. The drive shaft pump 80 produces the uid under pressure in the uid supply conduit 108 for engaging the brakes 17 and 18 and keeping them engaged until the driven shaft pump 81 increases to a substantial speed, the same as when the vehicle is started and driven in drive range.

Reverse drive through the transmission is obtained by moving the manual selector valve piston 127 into its R position. In this position, the groove 133 in the piston 127 connects the ports 137, 136 and 143. The conduitA 108 containing uid pressure from the pump 80 is connected with the port 137, and uid pressure is thus supplied to the conduits 147 and 146. For reverse drive, the uid pressure in the conduit 108 is obtained from the drive shaft pump .80 exclusive of the driven shaft pump 81, since the latter pump rotates in the reverse direction and does not supply fluid to its outlet conduit 95. The uid from the pump 80 flows through the conduits 91 and 109 to the uid pressure supply conduit 108 and the front pump relief valve 84 is effective for limiting the pressure in these conduits to a predetermined maximum.

The tluid pressure in the conduit 147 connected with the conduit 108 by means of the valve piston 127 is supplied beneath the piston 113 and on the piston 115 of the front pump relief valve 84 through the port 118, and this fluid pressure is effective to augment the action of the spring 122, tending to move the valve piston 113 upwardly to decrease the amount of uid ow between the upper end of the piston 113 and the edge of the port 119. The uid pressure applied to the piston 113 is effective to supply this force to the piston, since the piston 113 is larger in diameter than the piston 115 on which the uid pressure is also effective. The eiect of this force on the front pump relief valve piston 113 is to increase the pressure in the conduit 109 and in the connected conduits to a substantially higher pressure than that existing in these conduits for the forward drives. The reverse brake 19 is applied by fluid pressure from the conduit 146 which is connected with the conduits 108 and 109 by means of the ports 143 and 137 and the piston groove 133, and this increased pressure is supplied to the reverse brake servomotor 62 and particularly to the pistons 66 and 67 in this servomotor for applying the reverse brake 19 With a braking force which is greater than would otherwise be obtained with the fluid pressure regulated to a lower value as is used for the forward speed drives. An engagement of the brake 19, as has been previously described, completes the reverse drive power train through the transmission, and the increased force of application on the brake 19 due to the increased uid pressure functions to prevent slippage of the brake 19 due to the reaction on the brake which is greater than the reactions on the other brakes for the forward speed drives,

The 'pressure in the conduit 147 is supplied through the -conduits 214 `and1213 yto the -left'end ofthe converter valve piston 188, and the piston 18S acts through the spring 194 on the converter valve-piston 18S `tending to close the port -196 by the land m191 of the piston 18S. This port closing effect by the piston 185 has the net effect of maintaining thepressure in the torque converter 14 ksubstantially the same as in the forward drives even though the pressure in the conduit 108 and `connected conduits is-raised, as just described, by the front pump relief valve 84.

The reverse interlock valve 79 has the pressure output of the driven shaft pump 81'impressed thereon through the conduit 95, the ports 104, the conduit 212 and the port 209, and when the pump 81 is being driven by the shaft 1.1-rotating in the forward direction, there is sufiicient pressure applied -to the `piston 201 so that it is moved-against the spring 207 to connect the ports 211 and 210 byrmeans of the groove 206. Thus, whenthe selector valve piston -1'27 is moved into its reverse drive position to connect the ports 136, 143, and 137, with the vehicle moving forwardly at any substantial speed, the fluid from the-conduit 108 is drained to the sump through the conduits 147 and `214, the ports 211 and 210 and the groove 206, so that fluid under Vpressure is not available for 'engaging the reverse brake 19. The reverse drive power train can thus not be completed when there is any substantial forward movement of the vehicle.

The shuttle valve 77 advantageously functions to engage -the brake 18, in addition to the brake 17, for an initial drive in low speed through the transmission, when the -torque converter 14 is transmitting its maximum torque. As the speed of the vehicle increases to a predetermined low value, such as tive or ten miles per hour, the brake 1S is released by action of the shuttle valve, leaving the brake f17 solely effective to maintain the low speed power train completed, which Vat this time Ait is capable of doing since the torque conversion in the hydraulic torque converter had Vdecreased as the vehicle speed increases. Subsequently, when the vehicle speed increases still further, the second speedpower train is completed by engagement of the clutch 21 due to movement of the governor valve 83, and the low speed power train is automatically broken by the one-way engaging device40 overmnning. The shuttle valve '7 7 is so connected with the clutch yZ1 that the low speed lookup brake 18 cannot be engaged when the clutch 21 is engaged to complete the intermediate speed drive since fluid pressure in conduit 184, connected to clutch conduit 160, acts against valve 163 of shuttle valve 77 which maintains valve 162 moved to the left, port 173 is blocked by land 167 and uid pressure is .prevented from passing through conduit 172 to actuate servo-mechanism 61.

I wish it to be understood that my invention is not to be limited to the Vspecific constructions and arrangements shown and described, except only insofar as the claims may be so limited, as it will be understood to those skilled in the art that changes Amay be made without departing from the principles Aof the invention.

I claim:

l. ln a transmission, the combination of a driveshaft, a driven shaft, means for completing a low speed power train between said-shafts and including a friction engaging device and a one-way engaging device connected in parallel so that said friction engaging device supplements the one-way engaging devicein completing the power train, means for completing a higher speed power train between said shafts and 'including a `second friction engaging device causing said one-way engaging device to disengage when the Ahigher speed power train is completed, a hydraulic Episton for engaging rsaid Vfirst-named engaging device, a source of pressure, a 'valve for connecting said pressure Ysource .and said piston, a pump driven by said driven fshaft and `hydraulically connected with `said valve forrnovingrsaid valvef into 4a vposition to close communication between said vpressure source and said piston when the speed of said driven fshaftfreaches a predetermined value, a piston for engaging said-second friction engaging device, and conduit 'means for-selectivelyconnecting `said second-named piston'tandl saidxpressure source for lengaging said second friction engaging device, said first-named valve being connected with said conduit means for holding the first-named valve in apositionpreventing application of uid pressure to said first-namedpiston when fluid pressure -is applied to said second-named piston.

2. In a transmission, the combination of a drive shaft, a driven shaft, means for completing apower train between said shafts and including first and second engaging devices connected in parallel so that one supplements the other in completing the power train, and means responsive to the speed of -said' driven shaft vfor causing disengagernent of said first engaging device' when lapredetermined speed of-said driven shaft kis reached allowing the other engaging device to remain effective and maintain the power train completed, saidspeed responsive means including a pump driven by said ldriven shaft and effective on a shiftable valve for moving the valve to disengage said first engaging device when the speed of said 'driven shaft reaches a predetermined value, and-means for selectively applying pressure on said shiftable valve holding it in its position causingengagement of said first engaging device for maintaining saidpower train effective regardless of increases in the speed of said driven shaft.

3. In a transmission, the combination of a drive shaft, a driven shaft, means for completing a power train rbetween said shafts including iirst and second fluid pressure engaged friction engaging devices, one of which augmente the other yin completing the train, means for providing a second power train between said shafts and including a third fluid pressure engaged friction engaging device which with said first device completes the train, a source of iiuid pressure connectible with said friction devices, a valve hydraulically connected with said second device and movable from a first position applying iiuid pressure from said source to said second device for causing engagement thereof to a second position bleeding fluid pressure from said second device for causing disengagement thereof, and a hydraulic connection between said third device and said valve for holding said valve in its second position when uid pressure is applied to said third device.

4. In a transmission, the combination of avdrive shaft, a driven shaft, means for completing a power train between said shafts including first and second fluid pressure engaged friction engagingdevices one of which augments the other in completing the train, means for providing a second power train between said shafts and including a third fluid pressure engaged friction engaging device which with said first device completes the train, a source of fluid pressure connectible with said friction device, a valve hydraulically connectible with said second device, a spring maintaining said valve in a first position, said valve being movabie against the action of said spring from said first position applying fluid pressure from said source to said second device for engagement thereof to a second position bleeding fluid pressure from said second device for disengagement thereof, and a hydraulic connection between said third device and said valve for holding said valvein its second position whenuid pressure is applied to said third device.

5. In a transmission, the combination of a drive shaft, a driven shaft, means for completing a power train between said shafts including first and second friction brakes, one of which `augments the other in completing the train, means for providing a Vsecond power train betweensaid shafts and including a friction clutch which with said'first brake completes the train, uid pressure responsive means for engaging each of said brakes'and clutch, a source of fiuid pressure connectible'with said =fiuid pressure responsiverneans, a valve hydraulically/.con-

iected with said second friction brake pressure responsive means movable from a rst position applying uid pressure from said source to said second friction brake pressure responsive means for engagement of said second friction brake to a second position bleeding fluid pressure from said second friction brake pressure responsive means for disengagement of said second friction brake, and a hydraulic connection between said friction clutch pressure responsive means and said valve for holding said valve in its second position when uid pressure is applied to said friction clutch pressure responsive means.

References Cited in the le of this patent UNITED STATES PATENTS 2,595,969 McFarland May 6, 1952 2,640,373 Jandasek June 2, 1953 2,645,137 Roche July 19, 1953 2,679,768 Baule June 1, 1954 OTHER REFERENCES Automotive Industries, pages 26-30, Dec. 15, 1949. Modern Automatic Transmissions, Oct. 23, 1950, Chilton Company, Philadelphia, Pennsylvania. 

